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sequence explained by the following sentences:

First. The arbitrary number of the substance in the present list is given.

Second. The commercial name of each substance is recorded precisely
as it was labeled by the firm which furnished the coloring matter. When

*Plate 2 is an exception to this statement.



RESULTS. 19

two firms sent the same dye under the same or under different names the
circumstance is explicitly presented.

Third. Immediately after the commercial name that of the factory is
given. The dyes were obtained from three sources. Both the Actiengesell-
schaft fiir Anilinfabrikation and Meister, Lucius & Briining presented a large
number of dyes of their manufacture to the Johns Hopkins University. The
other dyes were purchased from the firm of Eimer & Amend, New York.

The following abbreviations are used throughout.

[A.] Actiengesellschaft fur Anilinfabrikation, Berlin (The Berlin Aniline Co.).

[A. A.C.] The Albany Aniline Color Works, Albany, New York.

[B.] Badische Anilin-und Sodafabrik, Ludwigshafen am Rhein (The Baden Co.).

[By.] Farbenfabriken vorm. Fr. Bayer & Co., Elberfeld (The Bayer Co.).

[C.] Leopold Cassella & Co., Frankfurt am Main.

[D.] Dahl & Co., Barmen.

[D. H.] L. Durand, Huguenin & Co., Basle and Hiiningen.

[G.] J. R. Geigy, Basle.

[I. ] Soci6t6 pour 1' Industrie Chimique (formerly Bindschedler & Busch), Basle.

[K.] Kalle & Co., Biebrich am Rhein.

[M.] Farbwerke vorm. Meister, Lucius & Briining, Hochst am Main (Meister,

Lucius & Bruning, Limited).
[O.] K. Oehler, Offenbach am Main.
[P.] Societ6 Anonyme des Matieres Colorantes de St. Denis, Paris.

Fourth. The chemical name of the absorbing medium is given.

Fifth. Reference is made either to the figure (or figures) and plate
which belong to the substance under discussion itself or to a figure which is
very much like the spectrograms of the dye considered.

Sixth. When possible, the number of the dye or the page of the inter-
mediate product, as found in the volume of Schultz & Julius, is recorded.

Seventh. The color and superficial character of the dry coloring matter
is suggested.

Eighth. The color of the solution as observed in a test-tube is followed
by the color in the cell. The change of color with thickness is often
significant.

Ninth. Then follows the concentration in grams of dry solvend in a
liter of solvent. The term "saturated" is to be understood in its general,
practical sense and not in the almost unattainable, theoretical sense.
Parenthetical, qualifying words, such as "(heated, filtered)," call attention
to the fact that the substance does not dissolve readily in water, or that the
solution contained gritty, foreign material, etc.

Tenth. Next is given the angle between the quartz plates forming the
top and bottom of the various cells used. In the same line the numbers
denote in order the minimum and maximum depths of solution through
which the light passed before acting upon the outer limits of the negative.
The intermediate thicknesses vary linearly, of course. The same angle is not



2O ATLAS OF ABSORPTION SPECTRA.

always associated with the same maximum depth, even when the minimum
thickness is unchanged, because several cells of different dimensions were
employed.

Eleventh. Finally, a brief account of the most noticeable characteristics
of the absorption spectrum, between the limits 0.20^ and 0.63/1, is furnished.

The results of eye-observations of the absorption spectra come first and
serye as checks on the photographic records. The data obtained visually
are qualitatively reliable for all strong bands between o. 40,* and o. 63/1. For
cases of very weak, general absorption much less importance must be
ascribed to the visual results because, unfortunately, the cells were not con-
structed so as to present side by side, in the field of view, two spectra, the
one of the light after passing through the absorbing solution, the other of
the unabsorbed light direct from the Nernst glower.

When the solution is fluorescent, or decomposes when ultra-violet light
falls upon it, or possesses a characteristic odor, etc., the facts are noted.
That the spectrograms are not distorted by the presence of fluorescent light,
but give as true records of the absorption spectra of fluorescent compounds
as they do for non-fluorescent solutions, was ascertained by direct experi-
ments. (In particular, see the record for solution No. 107.)

Lastly, the approximate wave-lengths of the maxima and minima of
absorption, as obtained from the spectrograms, are given, beginning near
o. 2O/ and continuing to 0.63/1. When the wave-lengths of the "ends" of a
region of absorption are given they obviously have significance only under
the conditions of thickness of absorbing layer, of concentration, of length
of photographic exposure, etc., which prevailed at the time when the
spectrogram was taken. The maxima are not subject to the same limita-
tions. The fact that the Seed films can produce spurious absorption bands
in the green must be again emphasized. (See figure 102, plate 26.)

When the end of the spectrogram, which marks the fading away of the
sensitiveness of the emulsion from the yellow to the orange, is practically a
straight line perpendicular to the length of the spectrogram it means that
there is no appreciable general absorption in this locality, but when the limit
just specified is approximately a right line inclined at an obtuse angle to the
positive direction of the axis of wave-lengths it signifies that appreciable
general absorption is present in this region.



TABULATED DATA OF ABSORPTION.



INTERMEDIATE PRODUCTS.

1. Amidonaphtholdisulphonic Acid H. (M.)

Fig. i, pi. i ; pp. 57 and 58, S. & J.

Grayish-white lumps. In solution
brownish yellow, colorless.

Saturated.

Angle 27.3'. Depth o to 0.25 mm.

No visible absorption. Intense blue
fluorescence. Ultra-violet absorp-
tion ends about 0.347/1.

2. /3-Naphtholdisulphonic Acid G. (M.)

Figs. 2 and 5, pi. i ; p. 51, S. & J.

Pinkish-white powder. In solution
colorless.

Saturated.

Angle 27.3'. Depth o to 0.25 mm.

No visible absorption. Intense blue
fluorescence. Absorption ends very
definitely and follows approximately
a straight line from 0.346/4 to 0.356/4.
Fig. 5 shows absorption exhibited by
a solution made by diluting a certain
volume of the saturated solution to
eight times its original value.
3. />-Nitraniline. (Powder, "extra.") (M.)

Page 12, S. & J.

Lemon-yellow powder. In solution yel-
low, faint yellow.

Saturated.

Angle 37.1'. Depth o to 0.34 mm.

No visible absorption is produced by
a column 6 cm. deep. Entire ultra-
violet absorption is weak. A region
of slight absorption from 0.20/4 to
0.255/4 is followed by transparency
as far as 0.34/4. Faint absorption
extends from 0.34/4 to 0.40/4. From
0.40/4 to 0.63/4 no absorption is no-
ticeable.

4. o-Nitrobenzaldehyde. (M.)

Page 61, S. & J-

White needles. In solution colorless.

Saturated.

Angle 31.2'. Depth O to 0.29 mm.

Extremely weak absorption from 0.20/4

to 0.24/4. Transparent from 0.24/4 to

0.63/4.

5. />-Nitrosodimethylaniline.

Fig. 3, pi. i ; p. 32, S. & J.

Dark-green, crystalline powder. In
solution brownish yellow, clear yel-
low.

Saturated.

Angle 23.4'. Depth o to 0.21 mm.



5. />-Nitrosodimethylaniline Continued.

Strong absorption in violet and blue
increasing towards the ultra-violet.
A remarkably transparent region
extends from 0.30/4 to 0.375/4. All
the strong lines between 0.324/4 and
0.363/4 are transmitted with almost
no decrease in intensity.* A very
round band stretches from 0.375/4 to
0.448/4 with its maximum at 0.432/4.
Complete transparency from 0.49/4
to 0.63/4.

6. Resorcine (techn. pure). (M.)

Fig. 4, pi. i ; p. 45, S. & J.

White, crystalline lumps. In solution
colorless.

Nearly saturated.

Angle 29.3'. Depth o to 0.27 mm.

No visible absorption. Very faint yel-
low in a layer a decimeter thick. Ab-
sorption ends very abruptly and
shows an almost vertical .right line
determined by 0.287/4 and 0.293/4.

COLORING MATTERS.

7. Naphthol Yellow. (A.) Naphthol Yellow

S. (M.) Sodium salt of dinitro-a-
naphthol-/?-monosulphonic acid.

Fig. 42, pi. 1 1 ; No. 4, S. & J.

Orange-yellow powder. In solution
brownish yellow, pure yellow.

Saturated (heated).

Angle 31.2'. Depth o to 0.29 mm.

Intense band in violet, ultra-violet side
invisible. Absorption decreases from
0.20/4 towards 0.335/4. Transparent
region around 0.335/4. A pair of
overlapping bands extends from
about 0.345/4 to 0.465/4. Their max-
imum absorption is at 0.385/4 and
their least absorption is at 0.41/4.
Very transparent from 0.465/4 to be-
yond 0.63/4.

8. Aurantia. Ammonium salt of hexanitro-

diphenylamine.

Fig. 39. pl.'io; No. 6, S. & J.

Reddish-brown crystals. In solution
dull red, yellow.

10 g. per liter (filtered).

Angle 42.5'. Depth o to 0.36 mm.

General absorption in violet. Absorp-
tion decreases from 0.20/4 towards
0.28/4. Transparent region from
0.28/4 to 0.33/4. Wide band from
0.33/4 to 0.49/4 with its maximum



* R. W. Wood. " On Screens Transparent only to Ultra-violet Light and their use in Spectrum Photography."
Phil. Mag., v. 5, Feb., 1903, pp. J57- 26 3-

. ' 21



22



ATLAS OF ABSORPTION SPECTRA.



8. Aurantia Continued.

at 0.41/1. As the concentration in-
creases the absorption encroaches
much faster on the transparent re-
gion in the ultra-violet than on the
limit in the yellow. Very trans-
parent to yellow and orange.

9. Fast Yellow. (B.) Sodium salt of

amidoazotoluene-disulphonic acid.

Somewhat similar to fig. 40, pi. 10;
No. 9, S. & J.

Brownish-yellow powder. In solution
brownish yellow, yellow.

15 g. per liter.

Angle 23.4'. Depth o to 0.21 mm.

Absorption in violet and blue. The
region of partial transmission in
the ultra-violet is not as complete
for solution No. 9 as for solution
No. 32. Also the boundaries of the
violet band are somewhat more defi-
nite for the former solution than
for the latter. The less refrangible
side of this band is more like the
corresponding region for solution
No. 129, fig. 13, pi. 3. Absorption
decreases gradually from 0.20/1. to
semi-transparency at about 0.34/1. A
wide, diffuse band extends from this
region to about 0.475/1. Its maxi-
mum is at 0.40/1. Transparent from
0.475/1 to 0.63/1.

10. Orange G. (A.) Sodium salt of benzene-

azo-jff-naphthol-disulphonic acid G.

Fig. 30, pi. 8; No. 14, S. & J.

Yellowish-red powder. In solution
red, yellow.

Saturated (heated).

Angle 21.3'. Depth o to 0.18 mm.

Strong absorption in blue and green.
Sharp on yellow edge. Two ultra-
violet bands meet at about 0.29/1 in
a semi-transparent spot. The maxi-
mum of the less refrangible band is
0.325/1. This strong band meets a
very weak one at 0.365/1. The center
of the weak band is 0.39/1. The
weak band joins an intense one at
0.42/1. This last band joins a still
stronger band, from which it is not
resolved, at 0.485/1. The maximum
of the stronger band is at 0.505/1.
Absorption ceases at 0.53/1. Com-
plete transparency to 0.63/1.

1 1. Ponceau 2 G. (M.) Sodium salt of

benzene -azo - naphthol - disulphonic
acid R.



n. Ponceau 2 G Continued.

Fig. 6, pi. 2; No. 15, S. & J.

Bright-red powder. In solution yel-
lowish red, yellow.

7 g. per liter (filtered).

Angle 27.3'. Depth o to 0.25 mm.

Comparatively weak band in the blue-
green, with a shadowy, fainter com-
panion on the yellow side. Absorp-
tion decreases gradually from 0.20/1
to 0.34/1. The nearly transparent
region from 0.34/1 to 0.44/1 is inter-
rupted by a very faint band having
its maximum at 0.39/1. The pair of
stronger bands extends from 0.44/1
to 0.545/1. Transparent from 0.545/1
to 0.63/1. Same empirical formula
as No. 10. No. 10 is derived from
the G acid, while No. n is a salt
of the R acid.

12. Chrysoidine. Hydrochloride of diami-

doazo benzene.

Fig. 7, pi. 2; No. 17, S. & J.

Reddish-brown powder. In solution
brown, yellow.

10 g. per liter (filtered).

Angle 23.4'. Depth o to 0.21 mm.

Absorption in violet, blue, and green
with maximum in the indigo. Ab-
sorption decreases from 0.20/1 to
-33f- Transparent from 0.33/1 to
0.36/1. A pair of broad, unseparated
bands absorbs from 0.36/1 to 0.54/1.
The band of greater refrangibility
is the more intense and has its max-
imum at 0.43/1. Transparent from
0.54/1 to 0.63/1. The less refrangible
band disappears first on dilution. A
five-strip negative shows that the
outer boundaries of the pair of bands
are steep and definite.

13. Chromotrope 6 B. (M.) Sodium salt

of ^-acetamidobenzene-azo- 1 :8-dioxy-
naphthalene disulphonic acid.

Fig. 8, pi. 2; No. 38, S. & J.

Grayish-brown powder. In solution
red, pink.

5.71 g. per liter.

Angle 11.7'. Depth o to o.n mm.

Strong absorption in green-yellow.
Transparent from 0.35/1 to 0.465/1.
A strong band has its beginning at
0.465/1 and its maximum at 0.515/1.
The less refrangible side joins a weak
companion band extending into the
orange and red. More dilute solu-
tions show that the intense band is
symmetrical with respect to its max-



COLORING MATTERS.



13. Chromotrope 6 B Continued.

imum until it joins the associated
band. More concentrated solutions
show very distinctly the weaker
band in the orange-red.

14. Azo Coccine 2 R. (A.) Sodium salt

of xylene-azo-a-naphthol-/>-sulphonic

acid.

Fig. 9, pi. 2 ; No. 50, S. & J.
Reddish-brown powder. In solution

salmon pink, salmon pink.
Saturated (heated).
Angle 27.3'. Depth o to 0.25 mm.
Narrow band in the blue-green. An

absorption band of very indefinite

edges extends from about 0.48/1 to

0.53/1 with its maximum at 0.505/1.

Transparent from 0.53/1 to 0.63/4.

15. Brilliant Orange G. (M.) Sodium salt

of xylene-azo-/J-naphthol-mono - sul-
phonic acid.

Fig. 31, pi. 8; No. 54, S. & J.

Cinnabar-red powder. In solution
yellowish red, deep yellow.

7 g. per liter.

Angle 23.4'. Depth o to 0.21 mm.

Intense absorption in blue-green and
blue. Very sharp on the yellow side.
Absorption decreases from 0.20/1 to
weak absorption at 0.295/1, then in-
creases to maximum absorption at
0.32/1. At 0.355/1 semi-transparency
obtains. A definite band has its
maximum at 0.395/1 and joins the
next band at 0.43/1. The next band
has its maximum at 0.48/1 and joins
the adjacent band at 0.505/1. The
final band has a maximum at 0.52/1.
Absorption ends at 0.545/1. Com-
plete transparency to 0.63/1. The
band at 0.395/1 disappears rapidly
with dilution. Same empirical
formula as solution No. 14.

16. Ponceau 2 R. (A.), (M.) Sodium salt

of xylene-azo-/J-naphthol-disulphonic
acid.

Similar to fig 55, pi. 14; No. 55, S. & J.

Brownish-red powder. In solution red,
pink.

5 g. per liter (heated).

Angle 27.3'. Depth o to 0.25 mm.

Hazy-edged band in the blue-green.
Similar absorption to that of solu-
tion No. 17 in the ultra-violet and
identical with it in the visible region.

17. Ponceau 3 R. (A.), (M.) Sodium salt

of ^r-cumene-azo - j8 - naphthol-disul-
phonic acid.



17. Ponceau 3 R Continued.

Fig. 55, pi. 14; No. 56, S. & J.

Dark-red powder. In solution red, pink.

5 g. per liter (heated).

Angle 29.3'. Depth o to 0.27 mm.

An absorption band is in the blue-
green. It has its maximum at 0.50/1
and extends from about 0.47/1 to
0.54/1. Transparent from 0.54/1 to
0.63/1.

18. Crystal Ponceau 6 R. (A.), (M.)

Sodium salt of a-naphthalene-azo-
/?-naphthol-disulphonic acid.

Similar to fig. 55, pi. 14; No. 64, S. & J.

Brownish-red crystals with golden re-
flex. In solution light red, pink.

5 g. per liter (heated).

Angle 27.3'. Depth o to 0.25 mm.

Hazy-edged band in the blue-green and
green. Similar absorption to that of
solution No. 17. The ultra-violet ab-
sorption, however, is somewhat more
intense and extends to greater wave-
lengths for solution No. 18 than for
solution No. 17. The visible band
extends from 0.465/1 to 0.56/1 with
its maximum at 0.51/1.

19. Bordeaux B. (M.) Sodium salt of o-

naphthalene-azo - J3 - naphthol-disul-
phonic acid.

Similar to fig. 19, pi. 5 ; No. 65, S. & J.

Brown powder. In solution red, red.

4.18 g. per liter.

Angle 42.5'. Depth o to 0.36 mm.

Hazy-edged band in the green. The
sides of the band in the green and
the orange end of the spectrogram
slope a little more for solution No.
19 than for No. 106. Band from
0.485/1 to 0.545/1, with maximum at
0.515/1. The least refrangible ends
for all the spectrograms slope, thus
showing that there is some general
absorption in the orange. More con-
centrated solutions show that the
greatest transparency occurs at
0.414/1. Same empirical formula as
No. 18.

20. Coccinine B. (M.) Sodium salt of p-

methoxy- toluene - azo - ft - naphthol-
disulphonic acid.

Similar to fig. 55, pi. 14; No. 73, S. & J.

Dark-red powder. In solution bright-
red, red.

13.64 g. per liter.

Angle 12.8'. Depth o to o.n mm.

Strong absorption in green-yellow.
Similar to solution No. 17, save that



ATLAS OF ABSORPTION SPECTRA.



20. Coccinine B Continued.

a weak absorption band seems to
have the limits 0.315/1 and 0.355/1,
with a maximum at 0.33/1. Intense
band from 0.465/1 to 0.555/1, with a
maximum at 0.510/1. Transparent
from 0.555/1 to 0.63/1. Very concen-
trated solutions or deeper layers
show that the transparent region on
both sides of 0.41/1 becomes opaque
much faster than the orange and red
region. Red is transmitted when all
shorter wave-lengths are absorbed
completely. The solution exhibits
strong dispersive power.

21. Eosamine B. (A.) Sodium salt of p-

cresol - methyl -ether-azo-a-naphthol-
disulphonic acid.

Fig. 52, pi. 13 ; No. 74, S. & J.

Reddish-brown powder. In solution
yellowish red, pink.

8.89 g. per liter.

Angle 21.3'. Depth o to 0.18 mm.

Strong band in blue-green and green.
Intense, round band from 0.465/1 to
0.565/1, with its maximum at about
0.52/1. Transparent from 0.565/1 to
0.63/1. Same empirical formula as
No. 20.

22. Erika B. (A.) Sodium salt of methyl-

benzenyl - amido - thio-xylenol-azo-a-
naphthol-disulphonic acid.

Fig. 57, pi. 15; No. 78, S. &J.

Reddish-brown powder. In solution
red, pink.

6.67 g. per liter.

Angle 19.5'. Depth o to 0.18 mm.

Strong absorption in blue, green, and
green-yellow. Two unresolved bands
absorb strongly from 0.46/1 to 0.59/1.
The more refrangible band shows
greater intensity than its companion
and has its maximum at 0.52/1. Slight
absorption in the orange is followed
by greater transparency in the red.

23. Emin Red. (A.) Sodium salt of methyl-

benzenyl - amido - thioxylenol-azo-/}-
naphthol-sulphonic acid.

Fig. 29, pi. 8 ; No. 80, S. & J.

Red powder. In solution red, pink.

Saturated (heated).

Angle 31.2'. Depth o to 0.29 mm.

Weak, hazy absorption in blue and
green. Strong absorption from 0.20/1
to about 0.35/1, then a rather rapid
decrease in absorption sets in. From



23. Emin Red Continued.

0.38/1 to 0.45/1 a semi-transparent re-
gion exists. A round band extends
from 0.45/1 to 0.54/1. Its maximum
is near 0.495/1. The less refrangible
side of this band is far more definite
than its ultra-violet edge. Trans-
parent from 0.54/1 to 0.63/1.

24. Janus Green. (M.) Chloride of safra-

nine-azo-dimethylaniline.

No. 81, S. & J.

Olive-green, crystalline powder. In so-
lution blue, blue.

4.6 g. per liter.

Angle 17.0'. Depth o to 0.14 mm.

Band in orange and orange-red. Trans-
parent to pure red. Very general ab-
sorption in ultra-violet, decreasing
gradually from 0.20/1 to 0.40/1. Trans-
parent from 0.40/1 to 0.515/1. The
absorption band begins at 0.515/1.

25. Tropaeoline O. (C.) Sodium salt of />-

sulphobenzene-azo-resorcinol.

Similar to fig. 37, pi. 10; No. 84, S. & J.

Brown powder. In solution wine-color,
yellow.

Saturated (heated).

Angle 25.5'. Depth o to 0.21 mm.

Faint absorption in the violet. Similar
absorption to that of solution No. 81.
Weak absorption from 0.20/1 to
0.275/1. Transparent from 0.275/1 to
0.325/1. A weak, hazy band extends
from 0.325/1 to 0.41/1 with its maxi-
mum around 0.37/1. Transparent
from 0.41/1 to 0.63/1.

26. Tropasoline OOO No. i. Sodium salt of

/>-sulphobenzene-azo-o-naphthol.

Similar to fig. 31, pi. 8; No. 85, S. & J.

Reddish-brown powder. In solution
red, salmon pink.

6.67 g. per liter.

Angle 21.3'. Depth o to 0.18 mm.

Absorption in violet, blue, and green.
Similar absorption to that of solu-
tion No. 15. Rather strong absorp-
tion continues from 0.20/1 to about
0.33/1 and then decreases rapidly to
semi-transparency. A tolerably trans-
parent region is from 0.35/1 to 0.37/1.
Three unresolved bands with maxima
at about 0.41/1, 0.48/1, and 0.52/1 fol-
low. The intermediate points of less
intensity of absorption are 0.435/1
and 0.450/1. At 0.545/1 the absorption
ceases. Transparent from 0.545/1 to
0.63/1.



COLORING MATTERS.



27. Tropseoline OOO No. 2. Sodium salt of

/>-sulphobenzene-azo-/8-naphthol.

No. 86, S. & J.

Bright, orange powder. In solution
deep red, salmon pink.

14 g. per liter.

Angle 21.3'. Depth o to 0.18 mm.

Visible absorption and spectrogram
identical with No. 26. Similar ab-
sorption to that of solution No. 15.
Nos. 26 and 27 have the same em-
pirical formulae, but differ by o and ft
in the naphthol.

28. Methyl Orange III. (P.) Sodium salt

of />-sulphobenzene-azo - dimethylani-

line.

Fig. 41, pi. ii ; No. 87, S. & J.
Ocher-yellow powder. In solution red,

yellow.

Saturated (heated).
Angle 27.3'. Depth o to 0.25 mm.
Absorption in blue and green. A strong

band extends from 0.36/1 to 0.525/1.

This band is very round with its

maximum at 0.44/11. Transparent

from 0.525/1 to 0.63/1.

29. Tropaeoline OO. (C.) Sodium salt of

^-sulphobenzene-azo - diphenylamine.

Similar to fig. 40, pi. 10 ; No. 88, S. & J.

Yellow powder. In solution yellowish
red, yellow.

6 g. per liter (heated and filtered).

Angle 25.5'. Depth o to 0.21 mm.

Delicate absorption in violet and blue.
Similar absorption to that of solu-
tion No. 32. The extreme ultra-
violet absorption is weak because the
lines near 0.23/1 show on all three
photographic strips. From 0.385/1 to
0.47/1 a weak absorption band obtains
with its maximum at 0.43/1. The
substance is very transparent to yel-
low and red. Nos. 29 and 32 have
the same empirical formulas. No. 29
is the para-compound and No. 32 is
the meta-. No. 29 shows weaker
absorption than No. 32.

30. Curcumeine. (A.) Mixture of nitrated

diphenylamine yellow with nitrodi-

phenylamine.

Fig. 12, pi. 3 ; No. 91, S. & J.
Ocher-yellow powder. In solution red,

yellow.

Saturated (heated).
Angle 27.3'. Depth o to 0.25 mm.



30. Curcumeine Continued.

Absorption in violet, blue, and blue-
green. Absorption complete at 0.20/1,
decreasing very gradually with com-
paratively definite contour to 0.455/1.
Transparent from 0.455/1 to 0.63/1.

31. Azo Acid Yellow. (A.) Azo Yellow,

concentrated. (M.) Mixture of
nitrated diphenylamine yellow with
nitro-diphenylamine.

Similar to fig. 12, pi. 3 ; No. 92, S. & J.

Ocher-yellow powder. In solution
brownish yellow, yellow.

Saturated (heated).

Angle 27.3'. Depth o to 0.25 mm.

Strong absorption of violet, blue, and
blue-green. Similar absorption to
that of solution No. 30. Absorption
is nearly complete and uniform from
0.20/1 to about 0.39/1. Then the ab-
sorption decreases in a gently slop-
ing curve to about 0.505/1. Trans-
parent to yellow and red. Nos. 30
and 31 are mixtures of the same con-
stituents and have very similar re-
gions of absorption.

32. Metanil Yellow. (A.) Sodium salt of

m - sulphobenzene-azo-diphenylamine.

Fig. 40, pi. 10 ; No. 95, S. & J.

Brownish-yellow powder. In solution
yellowish red, yellow.

4.29 g. per liter (filtered).

Angle 23.4'. Depth o to 0.21 mm.

Absorption in violet and blue. A band
with very indefinite boundary ex-
tends from about 0.36/1 to 0.47/1. The
maximum is near 0.41/1. Transparent
to yellow and red. A very concen-
trated solution shows complete ab-
sorption from 0.20/1 to 0.51/1 with a
semi-transparent spot at 0.34/1 and
maximum absorption at 0.40/1. Ab-
sorption ceases abruptly at 0.535/1.

33. Naphthylamine Brown. Sodium salt of

p - sulphonaphthalene-azo-a-naphthol.

Similar to fig. 11, pi. 3 ; No. 101, S. & J.

Brown powder. In solution reddish
brown, almost colorless.

1 1. 1 1 g. per liter (heated and filtered).

Angle 30.0'. Depth o to 0.45 mm.


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